I shoot Blues with TG, 3.7 for a 171PF. The Blues are completely coated so the only way you are getting build up (leading) anywhere would be by over crimping them. That goes for any coated lead. Shoot steel and go look at the ground, find a Blue Bullet you shot, the polymer is still on the lead. I've shot 1000 in 2 days, no build up other than carbon/burnt powder etc....